Cold Spray Deposition of High-Density Polyethylene Polymer Particles on Metal Substrates

In this paper, the use of the cold spray to deposit micron-sized high-density polyethylene (HDPE) particles on metal substrates was investigated. Previous attempts to cold spray polymers on metal substrates have been plagued by low deposition efficiencies and poor adhesion. Substrate and particle temperature, surface roughness and the thickness of a precursor film on the substrate were varied systematically. On smooth aluminum substrates at room temperature, increasing the temperature of the HDPE particles was found to improve the deposition efficiency with a maximum efficiency of DE = 0.81% for particles at T p = 80 °C. The aluminum surfaces were then sanded with different grit sandpapers. The average surface roughness imparted onto the aluminum substrate was found to improve deposition efficiency and adhesion. Using a 50-grit sandpaper which resulted in an average roughness of R A = 0.92 µm, a deposition efficiency of DE = 1.6% was measured for a T = 80 °C particle and a room temperature substrate. This is a 100% improvement over deposition while a 1100% increase in adhesion strength over a smooth aluminum surface was also found. Precursor LDPE coatings also increase the deposition efficiency even for the thinnest coating. Coatings one particle diameter thick were found to improve efficiency to DE = 3.35%.